Chimney breast removal

We're looking at removing the chimney breast from our living room, it takes up a vast amount of space and isn't functional as the chimney above has been removed.

Speaking to our builder who did the loft conversion for us (and removed the chimney above) he said it is not load bearing. Would this be an easy job for us to do ourselves? I'm concerned we don't have the correct tools and may make an almighty mess and get nowhere. Although I resent paying someone to do something we can do ourselves.

Has anyone done this themselves and would you recommend DIY or getting someone in to do it?

It's not something you could easily do yourself as (a) you will need to extend the joists over the area the chimney breast was, then board over the hole and plaster it (b) the insides of chimneys are absolutely filthy from, well, being chimneys. It would be a horrible job to do yourself and difficult unless you are very experienced at quite advanced DIY.